Chemical Equilibrium - Chemical Equilibrium 1. Consider the...

Chemical Equilibrium 1. Consider the following gas-phase reaction, at equilibrium, under conditions where the value of the equilibrium constant, K, is equal to 8: N 2 O 4 (g) <==> 2NO 2 (g), K = 8 Which of the following diagrams represents a snapshot of a very small portion of this system at equilibrium? 2. Given the following reaction and equilibrium constant, which statement is correct for this reaction at equilibrium. CO 2 <==> CO + 1/2O 2 , K c1 = 9.1 x 10-12 a. The forward rate will be the same as the reverse rate. b. The forward rate will be larger than the reverse rate. c. The forward rate will be smaller than the reverse rate. d. The concentration of CO 2 must be much smaller than the concentrations of both CO and O 2 .

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3. Given the equilibrium constants for the first two reactions below at 1000 o C, what is the equilibrium constant for the third reaction at the same temperature. (Assume that all species are in the gas phase.) CO 2 <==> CO + 1/2O 2 , K c1 = 9.1 x 10-12 (1) H 2 O <==> H 2 + 1/2O 2 , K c2 = 7.1 x 10-12 (2) CO 2 + H 2 <==> CO + H 2 O, K c3 = ? (3) 4. If the following reaction were at equilibrium in a closed vessel at a controlled temperature, what would be the effect of adding more H 2 to the reaction vessel and permitting the reaction to approach equilibrium again. CO + H 2 O <==> CO 2 + H 2 a. The concentrations of CO, H 2 O, and H 2 would all increase. b. The concentrations of CO, H 2 O, and H 2 would all decrease. c. The concentrations of CO and H 2 O would increase and the concentration of CO 2 would decrease. d. The concentrations of CO and H 2 O would decrease and the concentration of CO 2 would increase. 5. At 200 o C, nitrogen oxide reacts with oxygen to form nitrogen dioxide as follows: 2NO + O 2 <==> 2NO 2 , K c = 3 x 10 6 In a mixture of the three species at equilibrium, we can accurately predict that: a. The concentrations of both NO and O 2 will be much larger than the concentration of NO 2 . b. The concentrations of both NO and O 2 will be much smaller than the concentration of NO 2 . c. The concentrations of either NO or O 2 (and possibly both) will be much smaller than the concentration of NO 2 . d. The concentration of O 2 will be exactly one half the concentration of NO. e. The concentration of O 2 will be exactly twice the concentration of NO. 6. At 200 o C, nitrogen oxide reacts with oxygen to form nitrogen dioxide as follows: 2NO + O 2 <==> 2NO 2 , K c = 3 x 10 6 If a mixture of these three gases contains 0.10 M NO, 0.10 M NO 2 , and 0.01 M O 2 , then we can accurately predict that the reaction: a. is at equilibrium. b. is not at equilibrium and must proceed from left to right to reach equilibrium. c. is not at equilibrium and must proceed from right to left to reach equilibrium. d.

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